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Quick reference for math, physics, chemistry, and statistics formulas. Search and find what you need instantly.

Quadratic Formula
Math
x = (-b +- sqrt(b^2 - 4ac)) / 2a

Solves ax^2 + bx + c = 0

Where: a, b, c = coefficients

Pythagorean Theorem
Math
a^2 + b^2 = c^2

Relationship in right triangles

Where: a, b = legs, c = hypotenuse

Area of Circle
Math
A = pi*r^2

Area of a circle

Where: r = radius

Circumference
Math
C = 2*pi*r

Circumference of a circle

Where: r = radius

Slope Formula
Math
m = (y2 - y1) / (x2 - x1)

Slope of a line

Distance Formula
Math
d = sqrt((x2-x1)^2 + (y2-y1)^2)

Distance between two points

Midpoint Formula
Math
M = ((x1+x2)/2, (y1+y2)/2)

Midpoint of a line segment

Velocity
Physics
v = d / t

Speed with direction

Where: d = distance, t = time

Acceleration
Physics
a = (v - u) / t

Rate of change of velocity

Where: v = final, u = initial, t = time

Force
Physics
F = m * a

Newton's Second Law

Where: m = mass, a = acceleration

Kinetic Energy
Physics
KE = (1/2) * m * v^2

Energy of motion

Where: m = mass, v = velocity

Potential Energy
Physics
PE = m * g * h

Gravitational potential energy

Where: m = mass, g = gravity, h = height

Power
Physics
P = W / t

Rate of doing work

Where: W = work, t = time

Ohm's Law
Physics
V = I * R

Voltage, current, resistance

Where: V = voltage, I = current, R = resistance

Density
Chemistry
rho = m / V

Mass per unit volume

Where: m = mass, V = volume

Molarity
Chemistry
M = mol / L

Moles per liter

Where: mol = moles of solute, L = liters of solution

Ideal Gas Law
Chemistry
PV = nRT

Ideal gas behavior

Where: P = pressure, V = volume, n = moles, R = gas constant, T = temp

pH Formula
Chemistry
pH = -log[H+]

Acidity measure

Where: [H+] = hydrogen ion concentration

Mean
Statistics
x_bar = sum(x) / n

Average of values

Where: x = values, n = count

Standard Deviation
Statistics
sigma = sqrt(sum((x-mean)^2) / n)

Measure of spread

Probability
Statistics
P(A) = favorable / total

Chance of an event

This is a quick reference guide. For detailed explanations and examples, consult your textbook or teacher.